WOW! what a sad situation. It's tough being respectful to those who have not reciprocated. Been there!
I am wondering what your mom's wishes are. Do you think that your mom would want to see her family members? Is so, then it would be a very loving gesture to put hard feelings aside and allow these people to visit with her.
I do agree with other posters that getting in touch with your local hospice or palliative care chapter in your area would be very helpful.
I will be thinking of you
Warm Regards,
Wanna